An Investigation of Preservice Teachers' Understanding of Buoyancy

The purpose of this study was to examine the conceptual understandings of 55 elementary preservice teachers for the concept of buoyancy. This study used Ausubel’s Assimilation Theory (Ausubel, 1963) as a framework for a 15-week intervention that used pre/post concept maps (Cmaps), pre/post face-to-face semi-structured interviews, and drawings as evidences for change of formation of cognitive structures. Using a convergent parallel design and mixed methods approach, preservice teachers’ conceptions were analyzed using these evidences. Results of the study show that preservice teachers held both scientific conceptions and misconceptions about buoyancy as a force before and after an instructional intervention. Of importance were the existence of robust misconceptions about buoyancy that included inaccurate scientific knowledge about the foundational concepts of gravity, weight, mass, and density. The largest gains in scientific knowledge included the concepts of gravity, surface area, opposing forces, and the buoyant force. These concepts were consistently supported with evidence from post-concept maps, post, semi-structured interviews, and drawings. However, high frequencies of misconceptions were associated with these same aforementioned concepts as well as additional misconceptions about buoyancy-related concepts (i.e., weight, density, displacement, and sinking/floating). A paired t test showed a statistically significant difference (t = -3.504, p = .001) in the total number of scientifically correct concepts for the pre-concept maps (M = 0.51, SD = .879) and post-concept maps (M = 1.25, SD = 1.542). The Cohen’s d effect size was small, .47. Even through gains for the pre/post concept maps were noted, a qualitative analysis of the results indicated that not only were there serious gaps in the participant’s scientific understanding of buoyancy, after the instructional intervention an increased number of misconceptions were presented alongside the newly learned concepts. A paired t test examining misconceptions showed that there was a statistically significant difference (t = -3.160, p = .003) in the total number of misconceptions for the pre-concept maps (M = 2.709, SD = 1.449) and post-concept maps (M = 3.363, SD = 2.094) after the intervention. The Cohen’s d effect size was small, .43. Taken together, these results revealed that, in general, the preservice teachers had understandings of buoyancy that align with children in preschool and elementary school (Biddulph and Osborne, 1983; Grimellini-Tomasini et al., 1990; Halford, Brown & Thompson, 1986; Hsin and Wu, 2011; Kohn, 1993; Rappolt-Schlichtmann et al., 2007; Yin et al., 2008). Based on these findings, implications for this study suggest that elementary preservice teacher candidates should be carefully screened to ensure they have mastered foundational scientific knowledge that they are expected to teach to children. As such knowledge is a prerequisite to the development of pedagogical content knowledge, it is unlikely that large numbers of robust misconceptions will be significantly reduced or eliminated during a science methods course that is designed to focus on pedagogical content knowledge.